Computer Literacy Tests: Are You Human?

Today in Digg, I found this interesting article for Time.com by Lev Grossman

Every web surfer, in the course of his or her browsing, has been forced to stop and perform this weird little task: look at a picture of some wavy, ghostly, distorted letters and type them into a box. Sometimes you flub it and have to retype the letters, but otherwise you don’t think about it much. That string of letters has a name; it’s called a CAPTCHA. And it’s a test. By correctly transcribing it, you have proved to the computer that you are a human being.

This electronic hoop you have to jump through was invented in 2000 by a team of programmers at Carnegie Mellon University. Somebody at Yahoo! had gone to them, complaining that criminals were taking advantage of Yahoo! Mail–they were using software to automatically create thousands of e-mail accounts very quickly, then using those accounts to send out spam. The Carnegie Mellon team came back with the CAPTCHA. (It stands for “completely automated public Turing test to tell computers and humans apart”; no, the acronym doesn’t really fit.) The point of the CAPTCHA is that reading those swirly letters is something that computers aren’t very good at. If you can read them, you’re probably not a piece of software run by a spammer. Congratulations–you can have an e-mail account.

(…)

The faster that software evolves, and the harder it gets to distinguish between people and computers, the faster CAPTCHAS have to change. They might soon involve identifying animals or listening to a sound file–anything computers aren’t good at. (What’s next? Tasting wine? Composing a sonnet?) Von Ahn is confident that the good guys are still ahead for now, but the point at which software can reliably read CAPTCHAS is probably as few as three to five years away.